Fluid delivery device

ABSTRACT

A fluid delivery device may include a fluid driving mechanism for driving fluid out of a reservoir and an actuating mechanism for actuating the driving mechanism. The fluid delivery device may also include one or more sensors for monitoring operation of the fluid delivery device. The fluid delivery device may also include a chassis providing mechanical and/or electrical connections between components of the fluid delivery device.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of co-pending U.S. patentapplication Ser. No. 10/704291, filed on Nov. 7, 2003, which is acontinuation-in-part of co-pending U.S. patent application Ser. No.10/128,205, which are assigned to the assignee of the presentapplication and are incorporated herein by reference.

This application is related to U.S. patent application Ser. No. ______(Attorney Docket No. INSL-165) entitled CHASSIS FOR FLUID DELIVERYDEVICE, which is filed concurrently herewith, assigned to the assigneeof the present application, and incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to fluid delivery devices and moreparticularly, to an infusion pump for delivering therapeutic liquids toa patient.

BACKGROUND INFORMATION

Fluid delivery devices have numerous uses such as delivering a liquidmedicine to a patient subcutaneously. In a patient with diabetesmellitus, for example, ambulatory infusion pumps have been used todeliver insulin to a patient. These ambulatory infusion pumps have theability to offer sophisticated fluid delivery profiles includingvariable basal rates and bolus requirements. The ability to carefullycontrol drug delivery can result in better efficacy of the drug andtherapy and less toxicity to the patient.

Some existing ambulatory infusion pumps include a reservoir to containthe liquid medicine and use electromechanical pumping or meteringtechnology to deliver the liquid medicine via tubing to a needle and/orsoft cannula that is inserted subcutaneously into the patient. Theseexisting devices allow control and programming via electromechanicalbuttons or switches located on the housing of the device. The devicesinclude visual feedback via text or graphic screens and may includealert or warning lights and audio or vibration signals and alarms. Suchdevices are typically worn in a harness or pocket or strapped to thebody of the patient.

Currently available ambulatory infusion devices are expensive, difficultto program and prepare for infusion, and tend to be bulky, heavy andvery fragile. Preparing these devices for infusion can be difficult andrequire the patient to carry both the intended medication as variousaccessories. Many existing devices also require specialized care,maintenance, and cleaning to assure proper functionality and safety fortheir intended long-term use. Due to the complexity and high cost ofexisting devices many patients who would benefit from an ambulatoryinfusion pump are, nonetheless using inferior forms of therapy.

Accordingly, there is a need for a fluid delivery device with a reducedsize and complexity and that is relatively inexpensive to manufacture.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features and advantages will be better understood byreading the following detailed description, taken together with thedrawings wherein:

FIG. 1 is a top view of a fluid delivery device consistent with oneembodiment of the present invention.

FIG. 2 is an exploded view of one embodiment of a fluid drivingmechanism used in a fluid delivery device.

FIG. 3 is a perspective view of the fluid driving mechanism shown inFIG. 2 assembled into a chassis.

FIG. 4 is a perspective view of one embodiment of an actuating mechanismfor a fluid delivery device.

FIG. 5 is a plan view of the actuating mechanism shown in FIG. 4actuating the fluid driving mechanism shown in FIG. 2.

FIG. 6 is a schematic diagram of a fill sensor that may be used in afluid delivery device consistent with one embodiment of the presentinvention.

FIGS. 7A and 7B are schematic diagrams illustrating the operation of thefill sensor shown in FIG. 6 from a side view.

FIGS. 8A and 8B are schematic diagrams illustrating the operation of arotational sensor that may be used in a fluid delivery device consistentwith one embodiment of the present invention.

FIG. 9 is a perspective view of a chassis of a fluid deliver device withsensors positioned in the chassis consistent with one embodiment of thepresent invention.

FIG. 10 is a perspective view of a fluid driving mechanism engaging thesensors in the chassis shown in FIG. 9.

FIGS. 11A and 11B are schematic diagrams illustrating the operation of athread engaging mechanism moving from a non-thread-engaging position toa thread engaging position consistent with one embodiment of the presentinvention.

FIG. 12A is a perspective views of a thread engaging mechanism in afirst position consistent with one embodiment of the present invention.

FIG. 12B is a perspective views of a thread engaging mechanism of FIG.12A in a second position.

FIG. 12C is a top views of a thread engaging mechanism of FIG. 12A in asecond position.

FIG. 13 is an enlarged schematic side view of a drive wheel of a fluiddelivery device consistent with one embodiment of the present invention.

FIG. 14 is a schematic diagram of a fill sensor system that may be usedin a fluid delivery device consistent with one embodiment of the presentinvention.

FIGS. 15A, 15B and 15C are schematic diagrams illustrating the operationof an alternative rotational sensor that may be used in a fluid deliverydevice consistent with one embodiment of the present invention.

FIG. 16 is a bottom view of a fluid delivery device having a needle capconsistent with one embodiment of the present invention.

FIG. 17 is a schematic view of an activation system for a fluid deliverydevice consistent with one embodiment of the present invention.

DETAILED DESCRIPTION

Referring to FIG. 1, one embodiment of a fluid delivery device 200 isshown and described. In the exemplary embodiment, the fluid deliverydevice 200 is used to subcutaneously deliver a fluid, such as a liquidmedicine, to a person or an animal. Those skilled in the art willrecognize that the fluid delivery device 200 may be used to deliverother types of fluids. The fluid delivery device 200 may be used todelivery fluids in a controlled manner, for example, according to fluiddelivery profiles accomplishing bolus requirements, continuous infusionand variable flow rate delivery.

According to one embodiment, the fluid delivery device 200 may includeone or more batteries 210 for providing a power source, a fluidreservoir 230 for holding a fluid, a fluid driving mechanism 250 fordriving the fluid out of the reservoir 230, a fluid passage mechanism270 for receiving the fluid from the reservoir 230, a fluid passagemechanism 270 for receiving the fluid from the reservoir 230 and passingthe fluid to a destination, and a circuit board 290 with controlcircuitry for controlling the device. The fluid delivery device 200 mayinclude a chassis 100 that provides mechanical and/or electricalconnections between components of the fluid deliver device 200. Oneexample of the chassis 100 is disclosed in greater detail in U.S. patentapplication Ser. No. ______ (Attorney Docket No. INSL-165), which isfiled concurrently herewith and incorporated herein by reference. Thefluid delivery device 200 may also include a housing 202 to enclose thecomponents 210, 230, 250, 270, 290 and the chassis 100.

One embodiment of the reservoir 230 includes an outlet port 232 forallowing fluid to exit the reservoir 230. The reservoir 230 may alsoinclude an inlet port 234 for allowing the reservoir 230 to be filledwith fluid. One embodiment of the reservoir 230 is disclosed in greaterdetail in U.S. patent application Ser. No. ______ (Attorney Docket No.INSL-165), which is filed concurrently herewith and has beenincorporated by reference.

One embodiment of the fluid passage mechanism 270 includes atranscutaneous access tool 272, such as a needle and/or soft cannula,which is capable of penetrating the skin of a patient and passing thefluid into the patient. A fluid path such as tubing (not shown) may beused to fluidly couple the reservoir 230 to the transcutaneous accesstool 272. The access tool 272 is mounted to an insertion mechanism,which may include sliding carriages 274, 275, one or more springs 276,and a release member 280 (see FIG. 9). The sliding carriages 274, 275may be held in a first retracted position until the release member 280causes the sliding carriages 274, 275 to be released and the spring(s)276 drive the sliding carriages 274, 275 in the direction of the arrowinto an insertion position. The drive mechanism 250 may be used totrigger the release member 280 by engaging an arm 282 of the releasemember 280. In one embodiment, the sliding carriages 274, 275 firstinsert a needle and a soft cannula and then the sliding carriage 275withdraws the needle leaving the soft cannula in place. Varioustranscutaneous access devices and systems that may be accommodated in achassis in accordance with the present invention are disclosed in, forexample, U.S. Pat. No. 6,656,159 and U.S. patent application Ser. Nos.10/128,206,10/195,745, 10/260,192,10/261,003, all of which are herebyincorporated by reference.

Referring to FIGS. 2 and 3, one embodiment of the fluid drivingmechanism 250 includes a threaded drive rod 252 coupled to a plunger236. The plunger 236 is received in the fluid reservoir 230 (see FIG.10). In the illustrated embodiment, the drive wheel 256 threadablyengages and imparts linear motion to the threaded drive rod 252 toadvance the plunger 236 into the reservoir 230, thereby forcing fluidout of the reservoir 230. Alternatively, the threaded drive rod 252 maythreadably engage the plunger 236 and the drive wheel 256 may be fixedto the drive rod 252 to rotate the drive rod 252, which imparts linearmotion to the plunger 236.

One embodiment of the drive wheel 256 includes first and second ratchetwheel portions 258 a, 258 b and a hub 254 between the ratchet wheelportions 258 a, 258 b. The drive wheel 256 may be rotatably supported bythe chassis 100. In particular, the hub 254 may be supported by one ormore bearing surfaces 158 a-c on the chassis 100 (see FIG. 9). The drivewheel 256 is preferably be made of plastic and the drive rod 252 ispreferably made of metal or plastic.

An actuation mechanism is used to engage and incrementally rotate thedrive wheel 256. One embodiment of an actuating mechanism for the drivewheel 256 may include a linear actuator. A preferred linear actuatorcomprises a shape memory allow wire. As shown in FIGS. 2 and 3,preferably, the SMA wire comprises first and second shape memory alloy(SMA) wire portions 260 a, 260 b coupled to a pivotable drive engagingmember 262. The SMA wire portions 260 a, 260 bmay be formed as acontinuous SMA wire crimped to the pivotable drive engaging member 262as shown. The SMA wire portions 260 a, 260 bmay also be formed asseparate pieces of wire connected to the pivotable drive engaging member262 and may be connected in other ways known to those skilled in theart. The SMA wire may be made of nitinol, a well known alloy of nickeland titanium, or other SMA wire known to those skilled in the art. Thepivotable drive engaging member 262 may be made of an electricallyconductive material such as copper alloy.

As shown in FIG. 4, the SMA wire portions 260 a, 260 b may bemechanically secured to the chassis 100 and electrically connected tocontact points 160 a, 160 b on the chassis 100. In the illustratedembodiment, the SMA wire portions 260 a, 260 b are connected to crimpterminations 266 a, 266 b which are mounted in slots formed in anelectrically conductive portion of the chassis 100. The crimpterminations 266 a, 266 b may be made of a conductive material such ascopper alloy. The SMA wire portions 260 a, 260 b may also wrap aroundposts 161 a, 161 b or other mechanical structures, for example,extending from the chassis 100 to increase the functional length of theSMA wire.

The pivotable drive engaging member 262 may be pivotably coupled to apivot point 162 on the chassis 100, which also acts as an electricalcontact point. One embodiment of the pivotable drive engaging member 262includes arms 264 a, 264 b that engage teeth on the ratchet wheelportions 258 a, 258 b and incrementally rotating the drive wheel 256when the pivotable drive engaging member 262 pivots. The pivotable driveengaging member 262 may also include legs 268 a, 268 b that contactpoints 164 a, 164 b on the chassis 100 when the pivotable drive engagingmember 262 pivots. Alternatively, the pivotable drive engaging member262 may only include one arm and one leg.

The contact points 160 a, 160 b, 162, 164 a, 164 b provide an electricalconnection between the components of the actuating mechanism and thecontrol circuitry (not shown). In one embodiment, this electricalconnection is provided via conductive paths extending along the chassis100. The contact points 160 a, 160 b electrically connect the SMA wireportions 260 a, 260 b to actuator conductive paths 194 a, 194 b on thechassis 100. The pivot point 162 electrically connects the pivotabledrive engaging member 262 to a common ground conductive path 195 on thechassis 100. The contact points 164 a, 164 b electrically connect thepivotable drive engaging member 262 to actuator conductive paths 196 a,196 b. The conductive paths along the chassis 100 are shown anddescribed in greater detail in U.S. patent application Ser. No. ______(Attorney Docket No. INSL-165), which is filed concurrently herewith andhas been incorporated by reference. Those skilled in the art willrecognize other means for electrically connecting the components of theactuating mechanism to the control circuitry.

Referring to FIG. 5, the operation of the actuation mechanism isdescribed in greater detail. To charge the SMA wire portions 260 a, 260b, control circuitry (not shown) electrically connected to the chassis100 may selectively apply current to the SMA wire portions 260 a, 260 b,for example, via the conductive paths 194 a, 194 b (shown in FIG. 4).Current applied to a first SMA wire portion 260 a passes through the SMAwire portion 260 a and through the pivotable drive engaging member 262to the common ground conductive path 195 via the pivot point 162 (shownin FIG. 4), thereby energizing the first SMA wire portion 260 a withoutenergizing the second SMA wire portion 260 b. When charged, the firstSMA wire portion 260 a contracts and pulls the pivotable drive engagingmember 262 in a first direction indicated by arrow 20. When thepivotable drive engaging member 262 pivots in the first direction 20,the arm 264 a engages a tooth on the ratchet wheel portion 258 a causingthe drive wheel 256 to rotate one increment. The pivotable driveengaging member 262 pivots in the first direction 20 until the leg 268 bcontacts the contact point 164 b, electrically connecting the pivotabledrive engaging member 262 to the conductive path 196 b (shown in FIG.4). This activates a signal to the control circuitry (not shown) via theconductive path 196 b indicating that the control circuitry shoulddisable the current being applied to the first SMA wire portion 260 a.At all times one of the arms 264 a or 264 b is engaged by the toothportions of the drive wheel. The engaged arm 264 a or 264 b, thereforeprevents reverse rotation of the drive eliminating the need for aseparate pawl element. As shown in FIG. 13, the teeth of the wheelportions 258 a and 258 b are offset relative to one another therebymaximizing the tolerances for the interface between the arms 264 a and264 b and wheels 258 a and 258 b.

To initiate another pulse, the control circuitry applies current to thesecond SMA wire portion 260 b, for example, via the conductive path 194b and the contact point 160 b (shown in FIG. 4). When charged, thesecond SMA wire portion 260 b contracts and pulls the pivotable driveengaging member 262 in a second direction indicated by arrow 22. Whenthe pivotable drive engaging member 262 pivots in the second direction22, the arm 264 b engages a tooth on the ratchet wheel portion 258 bcausing the drive wheel 256 to rotate one increment. The pivotable driveengaging member 262 pivots in the second direction 22 until the leg 268a contacts the contact point 164 a, electrically connecting thepivotable drive engaging member 262 to the conductive path 196 a (shownin FIG. 4). This activates a signal to the control circuitry (not shown)via the conductive path 196 a indicating that the control circuitryshould disable the current being applied to the second SMA wire portion260 b.

Each incremental rotation of the drive wheel 256 advances the plunger inthe reservoir 230 to cause a discrete amount of fluid to be dispensed.The discrete amount of fluid to be dispensed is a function of the leadscrew pitch (i.e., threads/inch), the number of teeth on the ratchetwheel (that is, ratchet wheel tooth size) and the diameter of the fluidreservoir. In a preferred embodiment, for delivering U100 insulin fortreatment of Type I diabetes, the discrete amount of fluid to bedispensed is between about 0.25 μL and about 0.5 μL. The controlcircuitry alternates energizing the SMA wire portions 260 a, 260 b untila desired amount of fluid has been dispensed. One example of the controlcircuitry and control method is disclosed in greater detail in U.S.patent application Ser. Nos. 10/835727, 10/836525, and 10/836535, whichare fully incorporated herein by reference.

Examples of alternative fluid driving mechanisms and actuationmechanisms that may be used in the fluid delivery device 200 aredisclosed in U.S. Pat. Nos. 6,656,158 and 6,656,159 and U.S. patentapplication Ser. No. 10/704,291, all of which are incorporated herein byreference.

The fluid delivery device 200 may also include one or more sensors tomonitor operation of the fluid driving mechanism 250. For example, fillsensors may be used to sense a level of fluid in the reservoir 230 whenfilling the reservoir 230 with fluid and/or dispensing fluid from thereservoir 230. Rotational sensors may be used to sense that the drivingmechanism 250 is operating in accordance with expectations.

Referring to FIGS. 6, 7A and 7B, one embodiment of a fill sensorincludes a sensor bar 292 supported or mounted at one end by a sensorsupport 166 and extending across the path of the threaded drive rod 252.When the threaded drive rod 252 engages the fill sensor bar 292, thedrive rod 252 moves the fill sensor bar 292 and causes it to engage acontact point 165. Engaging the contact point 165 completes a circuitand activates a fill sensor signal to the control circuitry. The fillsensor bar 292 may be made of an electrically conductive material suchas a copper alloy and/or may be plated with a conductive material suchas nickel or gold.

At the point when the drive rod 252 causes the fill sensor bar 292 toengage the contact point 165, the plunger 236 is at a predeterminedlocation in the reservoir 230 and the amount of fluid in the reservoir230 is known. The fill sensor may be used when filling the fluiddelivery device 200 to indicate that the reservoir has been filled to apredetermined amount and/or to “wake up” the control circuitry in thefluid delivery device 200. Thus, in a preferred embodiment of thepresent invention, before the fill sensor has been triggered, the fluiddelivery device control circuitry is in a rest state characterized byminimal activity and power consumption. In such an embodiment, once thefill sensor is triggered, the control circuitry enters an active statecharacterized by higher activity and power consumption. The fill sensormay also be used when delivering the fluid to indicate that thepredetermined amount of fluid remains in the reservoir. Although oneembodiment of a fill sensor is shown and described, other configurationsmay be used to activate a fill sensor signal in response to apredetermined position of the drive rod. Referring to FIG. 14, in analternative embodiment, the fill sensing system comprises a plurality ofsensor bars 292 and contact points 165 placed at desired positions alongthe drive rod 252. The number and position of sensor bars and contactpoints may be selected for any desired resolution.

Referring to FIGS. 8A and 8B, one embodiment of a rotational sensorincludes a rotational sensor bar 294 supported or mounted at one end bya sensor support 168 and extending across a polygonal (or other camming)shaped portion of the drive wheel 256. The rotational sensor bar 294contacts a sensor contact point 169 to complete a circuit and activate arotational sensor signal to the control circuitry. When the drive wheel256 incrementally rotates, the hub 254 of the drive wheel 256 engagesthe rotational sensor bar 294 and moves the rotational sensor bar 294out of contact with the contact point 169. The activation anddeactivation of the rotational sensor signal indicates that the drivewheel 256 is rotating. The specific shape of the polygonal portion ofthe drive wheel may be selected to optimize the resolution of therotational sensor for a given application. In an alternative embodiment,as shown in FIGS. 15A, 15B and 15C, a rotational sensor may comprise asensor bar positioned to alternate between two contact points 169 a and169 b, thereby having 3 different states as shown in FIGS. 15A, 15B and15C, respectively, and a corresponding increase in resolution. Althoughone embodiment of a rotational sensor is shown and described, otherconfigurations may be used to activate a rotational sensor signal inresponse to movement of the drive wheel.

As shown in FIGS. 9 and 10, the sensor bars 292, 294 may be supported ormounted in the chassis 100. In this embodiment, the sensor supports 166,168 are electrically connected to the common ground conductive path 195extending along the chassis 100 and the contact points 165, 169 areelectrically connected to sensor conductive paths 197, 198,respectively, extending along the chassis 100. The sensor conductivepaths 197, 198 may be electrically connected to the control circuitry.

Referring to FIGS. 11A and 11B, the drive wheel 256 may include a threadengaging mechanism 240 that moves from a non-thread-engaging position toa thread engaging position. The non-thread-engaging position allows thethreaded drive rod 252 to pass freely through the drive wheel 256, forexample, when the reservoir of the fluid delivery device is beingfilled. The thread engaging position allows the threaded drive rod 252to be advanced when the drive wheel 256 is rotated, for example, whendispensing or delivering fluid from the reservoir.

One embodiment of the thread engaging mechanism 240 includes a tilt nut242 having threaded regions 244 a, 244 b. The tilt nut 242 may includeone or more pivot pins 246 that pivotably support the tilt nut 242within the drive wheel 256 (see FIG. 2). The tilt nut pins 246 provide apivot axis for the tilt nut 242 that is perpendicular to that of thedrive rod 252. The pivot axis is preferably offset from the center ofthe tilt nut 242. The tilt nut 242 is retained in the drive wheel 256 byportions of the chassis and by the tilt nut clip 1201, which is shownexploded in FIG. 12A. When the tilt nut 242 is in the open (tilted)position, the threaded regions 244 a, 244 b do not engage the threads onthe threaded drive rod 252 (FIG. 11A). When the tilt nut 242 is in theclosed position (FIG. 11B) the threaded portions engage the threadeddrive rod 252.

According to one embodiment, shown in FIGS. 12A and 12B, the tilt nut242 may also include a cam member 248 that engages guide surface 146 andcamming surface 148 on the chassis 100. Initially, the cam member 248engages the guide surface 146 and is maintained in the open (tilted)position (FIG. 12A). During initial rotation, the cam member 248 engagesthe camming surface 148 and the camming surface 148 forces the cammember 248 to pivot into the thread engaging position. The tilt nut 242may remain in the thread engaging position as the drive wheel 256rotates to advance the drive rod 252 and the plunger 236, therebydispensing fluid. Once the drive rod 252 is engaged by the tilt nut 252,the tilt nut is retained in the closed position by the surfaces of thechassis and the tilt nut clip and by the pressure of the drive rodagainst the offset pivot axis of the tilt nut 242 in the direction ofthe plunger 236. Notably, in a preferred embodiment, the stiction of theO-rings 501 on the plunger 236 provides sufficient anti-rotationalfriction to prevent the plunger from rotating with the drive rod 252.

FIGS. 16 and 17 show an alternative embodiment of a “wake-up” system fora fluid delivery device. FIG. 16 shows the bottom surface of a fluiddelivery device having a transcutaneous access tool 270 and a needle cap1601. As shown in FIG. 17, the needle cap is electrically and/ormechanically connected to a switch 1705 that couples a power source 1703and the control circuitry 1705. Removal of the cap 1601 closes theswitch between the power source 1703 and the control circuitry 1705thereby “waking” the fluid delivery device.

Although the illustrated embodiment shows the components mechanicallysecured to and electrically connected to a single chassis, thecomponents of the fluid delivery device consistent with embodiments ofthe present invention may be mechanically secured and/or electricallyconnected to other structures such as separate structural members or thehousing.

In summary, a fluid delivery device, consistent with one embodiment ofthe present invention, includes a fluid reservoir, a plunger received inthe fluid reservoir, a threaded drive rod coupled to the plunger toadvance the plunger in the fluid reservoir, and a drive wheel coupled tothe threaded drive rod. The fluid delivery device also includes apivotable drive engaging member including at least one arm configured toengage and incrementally rotate the drive wheel and at least first andsecond shape memory alloy (SMA) wire portions coupled to the pivotabledrive engaging member to pivot the pivotable drive engaging member. Inresponse to being charged, the first SMA wire portion is configured tocontract and pull the pivotable drive engaging member in a firstdirection and the second SMA wire portion is configured to contract andpull the pivotable drive engaging member in a second direction.

Consistent with another embodiment of the present invention, a fluiddelivery device includes a fluid reservoir, a plunger received in thefluid reservoir, a threaded drive rod coupled to the plunger to advancethe plunger in the fluid reservoir, a drive wheel coupled to thethreaded drive rod, and an actuating mechanism configured to engage andincrementally rotate the drive wheel. This embodiment of the fluiddelivery device also includes a rotational sensor extending across thedrive wheel. The drive wheel is configured to engage the rotationalsensor during rotation to cause the rotational sensor to contact aconductive path activating an electrical signal indicating rotation ofthe drive wheel.

Consistent with a further embodiment of the present invention, a fluiddelivery device includes a fluid reservoir, a plunger received in thefluid reservoir, a threaded drive rod coupled to the plunger to advancethe plunger in the fluid reservoir, a drive wheel configured tothreadably engage the threaded drive rod to impart linear motion to thethreaded drive rod when the drive wheel rotates, and an actuatingmechanism configured to engage and incrementally rotate the drive wheel.This embodiment of the fluid delivery device also includes a fill sensorextending across a path of the threaded drive rod. The threaded driverod is configured to engage the fill sensor when the plunger is at apredetermined location in the fluid reservoir to cause the fill sensorto contact an electrically conductive path enabling an electrical signalindicating an amount of fluid in the fluid reservoir.

Consistent with yet another embodiment, a fluid delivery device includesa fluid reservoir, a plunger received in the fluid reservoir, and athreaded drive rod coupled to the plunger to advance the plunger in thefluid reservoir. In this embodiment, the fluid delivery device alsoincludes a drive wheel configured to receive the threaded drive rod andincluding a thread engaging mechanism configured to move from anon-thread-engaging position to a thread engaging position in which thethread engaging mechanism engages threads of the threaded drive rod. Thedrive wheel is configured to impart linear motion to the threaded driverod when the thread engaging mechanism is in the thread engagingposition and the drive wheel rotates.

While the principles of the invention have been described herein, it isto be understood by those skilled in the art that this description ismade only by way of example and not as a limitation as to the scope ofthe invention. Other embodiments are contemplated within the scope ofthe present invention in addition to the exemplary embodiments shown anddescribed herein. Modifications and substitutions by one of ordinaryskill in the art are considered to be within the scope of the presentinvention, which is not to be limited except by the following claims.

1. A fluid delivery device comprising: a fluid reservoir; a plungerreceived in said fluid reservoir; a threaded drive rod coupled to saidplunger to advance said plunger in said fluid reservoir; a drive wheelcoupled to said threaded drive rod; a pivotable drive engaging memberincluding at least one arm configured to engage and incrementally rotatesaid drive wheel; and a linear actuator coupled to said pivotable driveengaging member to pivot said pivotable drive engaging member, whereinsaid linear actuator causes the pivotable drive engaging member to pivotwhen actuated.
 2. The fluid delivery device of claim 1, wherein thelinear actuator is a SMA wire.
 3. The fluid delivery device of claim 2,wherein the SMA wire comprises at least first and second SMA wireportions wherein activation of the first SMA wire portion causes thepivotable drive engaging member to pivot in a first direction andwherein activation of the second SMA wire portion causes the pivotabledrive engaging member to pivot in a second direction.
 4. The fluiddelivery device of claim 3 wherein said first and second SMA wireportions are part of a continuous SMA wire having first and second ends,wherein said pivotable drive engaging member is coupled between saidfirst and second ends.
 5. The fluid delivery device of claim 1 whereinsaid pivotable drive engaging member includes at least one legconfigured to contact an electrically conductive path to activate anactuator signal.
 6. The fluid delivery device of claim 5 wherein saidpivotable drive engaging member includes: first and second armsconfigured to engage and incrementally rotate said drive wheel as saiddrive engaging member pivots in respective said first and seconddirections.
 7. The device of claim 6, wherein the pivotable driveengaging member comprises first and second legs configured to contactelectrically conductive paths to activate actuator signals as said driveengaging member pivots in respective said first and second directions.8. The fluid delivery device of claim 6 wherein said drive wheelincludes first and second ratchet wheel portions configured to beengaged by said first and second arms of said pivotable drive engagingmember.
 9. The fluid delivery device of claim 6, wherein the first andsecond ratchet wheel portions comprise a plurality of teeth for engagingthe arms of the pivotable drive engaging member and wherein the teeth ofthe first ratchet wheel are offset relative to the teeth of the secondratchet wheel.
 10. The fluid delivery device of claim 3 furthercomprising a chassis mechanically interfacing said fluid reservoir, saiddrive wheel, said pivotable drive engaging member and said SMA wireportions.
 11. The fluid delivery device of claim 10 wherein saidpivotable drive engaging member is pivotably coupled to said chassis,and wherein said SMA wire is mounted to said chassis at said first andsecond ends.
 12. The fluid delivery device of claim 11 wherein saidchassis includes electrically conductive paths, wherein said first andsecond SMA wire portions are electrically connected to two of saidconductive paths configured to conduct electrical current to said SMAwire portions, and wherein said pivotable drive engaging member iselectrically connected to another one of said conductive pathsconfigured to act as a common ground.
 13. The fluid delivery device ofclaim 1 further comprising a rotational sensor extending across saiddrive wheel, said drive wheel being configured to engage said rotationalsensor during at least a portion of rotation of said drive wheel tocause said rotational sensor to engage and disengage an electricallyconductive path thereby activating a rotational sensor signal indicatingrotation of said drive wheel.
 14. The fluid delivery device of claim 13further comprising a chassis mechanically interfacing said fluidreservoir, said drive wheel, said pivotable drive engaging member andsaid SMA wire portions, wherein said chassis includes electricallyconductive paths, wherein one end of said rotational sensor is mountedto said chassis and electrically connected to one of said conductivepaths, and wherein said rotational sensor is configured to move into andout of contact with another of said electrically conductive paths toactivate said rotational sensor signal.
 15. The fluid delivery device ofclaim 1 wherein said drive wheel is configured to threadably engage saidthreaded drive rod to impart linear motion to said threaded drive rod.16. The fluid delivery device of claim 15 further comprising a fillsensor extending across a path of said threaded drive rod, said threadeddrive rod being configured to engage said fill sensor when said plungeris at a predetermined location in said fluid reservoir to cause saidfill sensor to contact a conductive path activating a fill sensor signalindicating an amount of fluid in said fluid reservoir.
 17. The fluiddelivery device of claim 16 further comprising a chassis mechanicallyinterfacing said fluid reservoir, said drive wheel, said pivotable driveengaging member and said SMA wire portions, wherein said chassisincludes electrically conductive paths, wherein one end of said fillsensor is mounted to said chassis and electrically connected to one ofsaid conductive paths, and wherein said fill sensor is configured tomove into contact another of said conductive paths to activate said fillsensor signal.
 18. The fluid delivery device of claim 15 comprising aplurality of fill sensors extending across a path of said threaded driverod, said threaded drive rod being configured to engage said fillsensors when said plunger is at predetermined locations in said fluidreservoir to cause said fill sensors to contact a conductive pathactivating fill sensor signals, each indicating an amount of fluid insaid fluid reservoir.
 19. The fluid delivery device of claim 1 whereinsaid drive wheel includes a thread engaging mechanism configured to movefrom a non-thread-engaging position to a thread engaging position inwhich said thread engaging mechanism engages threads of said threadeddrive rod, said drive wheel being configured to impart linear motion tosaid threaded drive rod when said thread engaging mechanism is in saidthread engaging position and said drive wheel rotates.
 20. A fluiddelivery device comprising: a fluid reservoir; a plunger received insaid fluid reservoir; a threaded drive rod coupled to said plunger toadvance said plunger in said fluid reservoir; a drive wheel coupled tosaid threaded drive rod; an actuating mechanism configured to engage andincrementally rotate said drive wheel; and a rotational sensor extendingacross said drive wheel, said drive wheel being configured to engagesaid rotational sensor during rotation to cause said rotational sensorto contact a conductive path activating an electrical signal indicatingrotation of said drive wheel.
 21. The fluid delivery device of claim 20further comprising a chassis mechanically interfacing said fluidreservoir, said drive wheel, and said actuating mechanism, wherein saidchassis includes electrically conductive paths, wherein one end of saidrotational sensor is mounted to said chassis and electrically connectedto one of said conductive paths, and wherein said rotational sensor isconfigured to move into and out of contact with another of saidelectrically conductive paths to activate said electrical signal. 22.The fluid delivery device of claim 20 wherein said drive wheel includesa hub configured to contact said rotational sensor.
 23. A fluid deliverydevice comprising: a fluid reservoir; a plunger received in said fluidreservoir; a threaded drive rod coupled to said plunger to advance saidplunger in said fluid reservoir; a drive wheel configured to threadablyengage said threaded drive rod, said drive wheel being configured toimpart linear motion to said threaded drive rod when said drive wheelrotates; an actuating mechanism configured to engage and incrementallyrotate said drive wheel; and a fill sensor extending across a path ofsaid threaded drive rod, said threaded drive rod being configured toengage said fill sensor when said plunger is at a predetermined locationin said fluid reservoir to cause said fill sensor to contact anelectrically conductive path enabling an electrical signal indicating anamount of fluid in said fluid reservoir.
 24. The fluid delivery deviceof claim 23 comprising a plurality of fill sensors extending across apath of said threaded drive rod, said threaded drive rod beingconfigured to engage said fill sensors when said plunger is atpredetermined locations in said fluid reservoir to cause said fillsensors to contact a conductive path activating fill sensor signals,each indicating an amount of fluid in said fluid reservoir.
 25. Thefluid delivery device of claim 23 further comprising a chassismechanically interfacing said fluid reservoir, said drive wheel, andsaid actuating mechanism, wherein said chassis includes electricallyconductive paths, wherein one end of said fill sensor is mounted to saidchassis and electrically connected to one of said conductive paths, andwherein said fill sensor is configured to move into contact with anotherof said electrically conductive paths to activate said electricalsignal.
 26. A fluid delivery device comprising: a fluid reservoir; aplunger received in said fluid reservoir; a threaded drive rod coupledto said plunger to advance said plunger in said fluid reservoir; a drivewheel configured to receive said threaded drive rod, said drive wheelincluding a thread engaging mechanism configured to move from anon-thread-engaging position to a thread engaging position in which saidthread engaging mechanism engages threads of said threaded drive rod,said drive wheel being configured to impart linear motion to saidthreaded drive rod when said thread engaging mechanism is in said threadengaging position and said drive wheel rotates; and an actuatingmechanism configured to engage and incrementally rotate said drivewheel.
 27. The fluid delivery device of claim 26 further comprising achassis mechanically interfacing said fluid reservoir, said drive wheel,and said actuating mechanism, wherein said chassis includes a cammingsurface configured to engage said thread engaging mechanism to move saidthread engaging mechanism from said non-thread-engaging position to saidthread engaging position.